To find out what helped the series become such a phenomenon, we have to go back to season 2's climatic " Blackwater" episode.

"Blackwater" not only brought "Thrones" to the masses; it was also one of the most costly episodes ever produced for television.

Here's how the epic $8 million episode came together.

Preparing For Battle

According to series creators Dave Benioff and Dan "D.B." Weiss, preparation for the Battle of Blackwater episode started all the way back in season 1.

"This whole story of Blackwater goes back to the first season ... we were supposed to have that battle with Tyrion and we ended up not able to shoot it," Benioff told EW. "We always promised ourselves, we're gonna have our major battle."

That major battle would turn out to be season 2's penultimate episode, "Blackwater." However, bringing a key conflict to life would be a serious production and financial challenge. Luckily, the creators were able to go to the source for help.

"Dave and Dan gave me the hardest episode of the season," author of the series and writer of the episode George R.R. Martin told GQ. "I think it was their subtle revenge for creating such a difficult-to-produce show."

Hardest episode is an understatement. In the second book, "A Clash of Kings," the Battle of Blackwater is a war by land and sea that blows up a fleet of ships and takes up six chapters. Putting it together would undoubtedly be a challenge — but not as challenging as getting HBO to pay for it.

"You Guys Need A Million Dollars?"

According to E! Online, an average episode of "Game of Thrones" costs $6 million, making it one of the most expensive series on television.

"Blackwater" is not your typical episode, so the creators went to HBO to ask for more money, they told GQ:

Benioff: "We had one really intense conference call with the HBO brass. It was awkward: They said, 'So, what are you guys talking about, an extra $500,000?' We said, 'Noooo....' 'You guys need a million dollars?' 'Ummmm....'

Weiss: "I think we asked for $2.5 million. We got $2 million-something. That's a lot of money in TV."

Benioff told EW the scene used more effects than any other episode up until that point.

"We try to avoid excessive VFX on the show, but with 'Blackwater' there was no alternative," Benioff told EW. "[Visual effects team members] Steve [Kullback] and Rainer [Gombos] look over a large team of tech wizards and what they've accomplished is, in our completely unbiased opinion, some of the best effects work in television history."

All of it would go into making "Blackwater," but would the price tag be worth it for HBO and "Game of Thrones"?

A Fire And Blood Phenomenon

The use of "Wildfire" on Stannis' fleet would be one of the most spectacular scenes in the episode.Game of Thrones/HBO